Cooper quartet correlations in infinite symmetric nuclear matter

TL;DR

This paper develops a variational theory to study quartet correlations in infinite symmetric nuclear matter, revealing coexistence of pair and quartet condensates and their impact on physical properties.

Contribution

It introduces an extended BCS-type wave function to account for both pair and quartet correlations in nuclear matter, advancing understanding of fermionic condensations.

Findings

Coexistence of deuteron and alpha condensates in nuclear matter.

Modification of quasiparticle dispersion by quartet correlations.

Hierarchical structure of in-medium cluster formations.

Abstract

We investigate the quartet correlations in four-component fermionic systems at the thermodynamic limit within a variational many-body theory. The Bardeen-Cooper-Schrieffer (BCS)-type variational wave function is extended to the systems with the coexistence of pair and quartet correlations at zero temperature. Special attention is paid to the application of the present framework to an alpha-particle condensation in symmetric nuclear matter, where the coexistence of deuteron and alpha condensations is anticipated. We also discuss how physical properties, such as quasiparticle dispersion, can be modified by the pair and quartet correlations and show a hierarchical structure of in-medium cluster formations in infinite nuclear matter. The present results may also contribute to the interdisciplinary understanding of fermionic condensations beyond the BCS paradigm in many-body systems.